Dunkirk: Retreat to Victory

Preface

This book tells the story, from the point of view of the British Expeditionary Force (BEF), of the campaign in France and Flanders in 1940 that led to the evacuation from Dunkirk. It does not quite end there, for the British Army also participated in the fighting south of the Somme, a campaign almost unknown to most British readers. This was followed by yet another evacuation of nearly 150,000 British soldiers of what was sometimes called the ‘Second BEF’.

The story of the saving of the BEF at Dunkirk has been told often, perhaps too often in the context of ‘the dithering of Hitler and the immortal exploits of the little ships – to quote Brian Bond, a distinguished historian of the period. Less well known is the narrative of continuous hard fighting experienced by the main body of the BEF in the three weeks between the German invasion of France on 10 May 1940 and the end of the evacuation from Dunkirk on 4 June. When I mentioned that I was writing a book about the campaign to a field marshal, a distinguished veteran of the Second World War (but not of Dunkirk), his reaction was that there was plenty to say about the actual evacuation. He added, ‘But the trouble is that the BEF did so little fighting before the evacuation.’ The implication was that there was little to say on the subject. It has been my purpose to show that not only did the BEF have to fight hard, it had to do so while carrying out that most difficult phase of war, a withdrawal while in contact with a ruthless enemy. Many armies in history have found retreat more than they can handle and have disintegrated before surrendering, or have been cut to pieces with huge loss. The former was the fate of both of Britain's allies in this campaign.

The BEF of 1940 was not the best-trained or best-equipped army that has left our shores to fight overseas. Years of political dithering had seen to that. It was certainly nothing like as well trained as the superb German Army, throughout the Second World War perhaps one of the finest fighting organizations the world has ever seen. Viewed overall the BEF in 1940 lacked that difficult-to-define flair that marks out brilliant soldiers from plain practitioners of the art. Or put another way they were not ‘quick enough on the draw’ tactically speaking. Of course there were exceptions – some individuals and units showed this flair – but it did not run through the whole force like a common thread. This comes only with training and good leadership. The BEF did not have enough time to train. It was not the fault of the soldiers, and the reasons for it are made plain in this book.

But, despite that, the BEF gave the Germans a testing run for their money, and this is made clear in the German assessment of the British soldier as a ‘fighter of high value’, in the report quoted in my final chapter. How much more challenging it would have been for the Germans had the BEF been better equipped and trained. It is hard to fault much of the leadership of the BEF – some of it was outstanding, as the reader will discover. From the ashes of the 1940 campaign in France and Flanders emerged many of the successful senior commanders in the British Army in the Second World War, starting with the man who would be the Chief of the Imperial General Staff from 1941 to the end of the war, Field Marshal Sir Alan Brooke (later Viscount Alanbrooke). The others include, and the list is not exhaustive, future army commanders Montgomery, Alexander, McCreery and Dempsey; corps commanders Lumsden, Horrocks, Ritchie (who briefly commanded Eighth Army) and Crocker; and divisional commanders Adair, Rennie and Whistler. These officers proved themselves in moments of the utmost danger in 1940, which would have broken lesser men, and sometimes did.

The soldiers they led were indomitable and were no different from their predecessors, in the words of Field Marshal Wavell writing of an earlier war, ‘whose humorous endurance of time and chance lasts always to the end’. Of course there were instances where discipline broke down, of cowardice and of failure, but in the main these were a tiny minority. The manner in which they fought earned the respect of their opponents, which could not be said of their French and Belgian allies. It cannot be said too often that the retreat was not caused by failure on the part of the BEF; it was the consequence of their allies on either flank losing the battle. But in the end for the BEF it was a retreat to victory like that at Corunna in Spain in 1809 or Burma in 1942. Throughout, the soldiers of the BEF thought of themselves as better than their opponents, and this bloody-minded conceit sustained them in the darkest moments.

This is their story.

1

TWENTY WASTED YEARS

History provides many examples of a British Army being asked to operate under appalling handicaps by the politicians responsible for British policy, but I doubted that the British Army had ever found itself in a graver position than that in which the governments of the last twenty years had placed it.

Major General Noel Mason-MacFarlane briefing the press, 15 May 1940¹

At 1334 hours on 3 June 1940, Admiral Jean Abrial, the French commander of the Dunkirk area, was ordered by the French high command to leave and embark for England. The British evacuation, less some of the more seriously wounded in hospitals and dressing stations, was complete. In peacetime Dunkirk was a busy commercial port; now chaos reigned in the town. The beaches were under German artillery fire, while French soldiers, sailors and civilians looted the burning buildings. British destroyers waited until darkness before heading for the moles to take off the French rearguard. Vice Admiral Bertram Ramsay, the Flag Officer Dover, asked that ‘in return for the British effort on behalf of the French Army’ the maximum number of British wounded should be included in the evacuation.

At about 2200 hours, Abrial burned his codes and embarked but, reluctant to leave his command, remained off the port and beaches until 0200 hours the next morning, before his ship steamed for Dover. Meanwhile all night crowds of weary men boarded a miscellany of craft including tugs, pleasure craft, cross-Channel ferries, launches, motor-boats and destroyers that came alongside the moles at Dunkirk. At first light, on the orders of General Barthélemy, commanding the Flanders fortified sector, the French 68th Infantry Division that had been holding ground to the south-west of Dunkirk disengaged and withdrew to the port. Few of the division got away: a flood of deserters from the First, Seventh and Ninth French Armies, who had hidden in the town, emerged and blocked the route of Barthélemy's rearguard to the last ships. In desperation, some officers sent their men to the dunes in the hope of eventually finding ships off the beaches.

That morning the Germans entered Dunkirk to find the moles and approaches packed with enemy soldiers. For miles along the beaches lay a trail of military impedimenta: steel helmets, guns, trucks, small arms of all descriptions, boots and clothing, gas masks, wireless sets – and the bodies of men caught in the open on the beaches, killed in the fighting to hold the perimeter, or washed in by the tide from ships and vessels bombed and machine-gunned by the Luftwaffe. Off the beaches the wreckage of all manner of vessels protruded above the surface of the sea, or lay like stranded whales at low tide, their hulls and decks littered with dead French and British soldiers.

Before the French commanders surrendered to the Germans at the Hôtel de Ville, they signalled General Weygand, the French Supreme Commander, that nothing more could be done, adding that ‘Admiral Abrial considers the operation of the English [sic] this night magnificent’. Admiral Darlan, the French Chief of the Naval Staff, signalled his thanks to the British Admiralty and to Admiral Ramsay. Nearly half as many French troops as British had been evacuated, but thousands more were marched off to Germany as prisoners. Perhaps some of them overheard the remark made by an unknown German officer: ‘Where are the Tommies? Tommies gone and you here. You crazy?’ The recriminations that ensued among the Allies were bitter, stoked among others by the Anglophobes Darlan and Marshal Philippe Pétain, the latter soon to be the head of the French government.

The arguments last to this day, and can be traced back to a misalignment of French and British perceptions about the situation as the Battle of France unfolded in May 1940. The French government, believing that the war was lost, with their army totally defeated and heading for destruction, a successful military outcome was unimaginable. They wanted the British to fight long enough in northern France, and eventually at Dunkirk, to buy time for both France and Britain to obtain an acceptable peace for both nations. The French did not articulate this desire, they merely hinted at it, hoping that this was what the British would do. The British had no intention of falling in with this vague and probably fruitless concept; they had an escape route and would take it, to live to fight another day. Brigadier Swayne, head of the British Military Mission to General Georges, commander of the French North-East Front, remarked: ‘We who live in a small island regard the sea as a high road. For the French it is the limit of their country. To take to the sea would be to abandon their country and would be disgraceful.’ To the British the evacuation at Dunkirk was a ‘miracle’; to the French it was desertion. How did it come about?

*

The words of General Mason-MacFarlane quoted at the head of this chapter provide part of the clue to the situation in which the British found themselves in May and June 1940. Although often forgotten now, it was not until February 1939, only seven months before the outbreak of the Second World War, that the British government decided to commit a small part of the army to the continent in the event of German aggression in the west. This field force was to consist of four regular infantry divisions, the first two to arrive in their assembly area in France thirty days after mobilization. It was smaller than the British Expeditionary Force (BEF) of 1914, less well trained and lacking much essential equipment.

Britain had ended the First World War twenty years earlier with the best-trained, best-equipped and best-commanded army in her history. In the space of three months in the autumn of 1918, this army had fought and won a series of battles, each bigger than any in which it was to engage in the Second World War. By November 1918, the British Army had soundly defeated the German Army, taking more prisoners and guns than the French and American armies put together. No other army was in the same league. This was to change as the years passed. With the ‘war to end all wars’ won, Britain rapidly disarmed, while others talked about it and did nothing, or – like Germany – having disarmed, secretly rearmed. Starting in 1918, successive British governments assumed that there would be no major war for ten years, and from 1928, as each year passed, the assumed decade of peace was moved forward with it. The armed services were reduced, and for thirteen years these small forces were kept starved of equipment. In March 1932, seeing that others had not followed this example, leaving Britain dangerously weak, the government abandoned the ten-year policy and a policy of rearmament was discussed, though little was actually done.

One would have lingering wars with little cost;

Another would fly swift, but wanteth wings;

A third thinks, without expense at all,

By guileful fair words peace may be obtain'd.²

In January 1933 Hitler became German chancellor. The following year the British finally decided on a measure of rearmament, but by 1936, when Hitler's troops reoccupied the Rhineland in breach of the 1925 Locarno Treaty, there was little to show for it. By then Italy and Germany had formed the Axis alliance and were beginning to build large armies, while Japan – which joined the Axis a year later – was spending 46 per cent of her national income on armaments. In April 1938 London concluded that in the event of war with Germany the British contribution to the Allied response should be provided mainly by naval and air forces. A large army would not be sent to the continent of Europe; instead its role would be confined to defending the United Kingdom and her overseas territories. So priority in the way of equipment for the army was given to anti-aircraft guns and coastal batteries. The five divisions of the field force trained and were fitted out for imperial defence, not for continental warfare against a first-class enemy. The Territorial Army (TA) was to be supplied only with training equipment. This was the state to which successive governments had reduced the British Army.

This army had been the first to use the tank in battle, in September 1916. After the First World War two men, Captain Basil Liddell Hart and Major General J. F. C. Fuller, preached that the future lay in massed formations of fast tanks, supported by mobile self-propelled artillery and infantry carried in tracked armoured vehicles. Instead of hammering away at a wide sector of front, as in 1914–18, the armoured formations would exploit a weak spot in the enemy defences and pour through in what Liddell Hart and Fuller called an ‘expanding torrent’, to attack vital points in the enemy's rear and paralyse him. In 1926, the British Army set up an experimental mechanized force to practise and develop these theories of armoured warfare. But two years later the conservative element within the army disbanded the force. Mechanization was eventually carried out but far too late for the whole army to assimilate the changed tactics that might have brought success in the ensuing campaign in France and Flanders in 1940.

Once the British government woke up to the dangerous situation that faced the country thanks to the failure to rearm, the Royal Navy and the Royal Air Force were rapidly, if belatedly, re-equipped (not always with the happiest results, but that is outside the scope of this book). The tasks envisaged for the Royal Navy did not impinge on operations ashore in France and Flanders in 1940. The role assigned to the RAF most certainly did. The 1938 re-armament programme called for a greatly expanded RAF capable of defending Britain and mounting bombing offensives against Germany. There was no provision for support of land operations that would have meant sending a large, mobile air force overseas. Although a proportion of the RAF's bombers might be stationed forward in France to decrease the range to German targets, these were expressly not in support of ground operations. The RAF had stoutly defended its independent existence since its creation in April 1918, and preached a doctrine called the indivisibility of air power. In essence, the RAF would decide where and how air power would be exerted. Simply expressed, the RAF's thinking was ‘We will win the war on our own, and certainly will not waste our time supporting you brown jobs’ – or, if addressing the Royal Navy, ‘you blue jobs’.³

Rearmament in Britain was boosted by the aftermath of the Munich meeting in the autumn of 1938, when it became apparent that despite the appeasement of Hitler by the British Prime Minister, Neville Chamberlain, peace was not at hand. The snag with rapid rearmament is that putting it into effect is considerably more difficult and time-consuming than deciding to go ahead with it. This is especially true if, as was the case with Britain, the armaments industry had been allowed to run down. Factories have to be geared up for a hugely increased rate of production, while new workshops may have to be built to augment existing ones that could not cope with the expanded output required. Weapons and equipment that are still in the trial stage of development, or even just a gleam in the eye of the inventor, may need further trials before production in quantity can begin. Finally soldiers have to be trained to use and maintain the new equipment. But it does not end there. Introducing a new gun into service usually involves designing and manufacturing a new type of ammunition. So yet more plant is required, and a workforce trained to operate it. Equipment needs spares to ensure that it is kept serviceable. These have to be manufactured too, sometimes in vast quantities. Rearming on a large scale involved placing orders abroad to supplement British production, or even to manufacture every piece, from complete equipments to spares. As in 1914–18, the bulk of these orders went to the United States. The British government should have been well aware of all the hurdles that had to be overcome in the great rearmament catch-up effort. Britain had undergone exactly the same experience in the First World War only twenty years earlier. There were plenty of people around in senior government posts who could remember this, and there was no excuse for being caught out a second time.

In February 1939, in addition to committing the army to deploying in France, and therefore to a war for which it was not equipped or trained, the British government doubled the size of the TA to 340,000, creating twelve new infantry divisions with supporting arms – thus compounding the problem the country already faced in the race to rearm. If that was not enough, a limited form of conscription was introduced. The conscripts needed equipment on which to train too.

Events now speeded up. On 14 March 1939, German troops invaded what had been left of Czechoslovakia after the dismemberment of the country at Munich the previous year. On 29 March, six months before the outbreak of war, Anglo-French staff talks began. The French made clear that the defence of their own territory was their first priority in the event of invasion by Germany. When this had been secured, they intended remaining on the defensive until they had built up sufficient resources for a counter-offensive, while at the same time maintaining an economic blockade of Germany. The British had no difficulty in agreeing this strategy; indeed, since their contribution was so small, they could hardly do otherwise. At this stage in the talks the British revealed that there would be a gap of eleven months between the arrival in France of the first two divisions and the advent of the second two. The build-up for the counter-offensive would, the Allies agreed, be a matter of years not months, given that there was so much ground to make up in terms of equipment and manpower. They had to assume that they could force a stalemate on the Germans and ensure a repetition of the static warfare on the Western Front of most of the years 1914–18. This assumption was made despite the advances in warfare and equipment since 1918, especially in tanks and aircraft. It was a strategy based on the hope that the enemy would do what suited the Allies.

As the weeks went by, the British were able to tell the French that their proposed contribution was a general headquarters and two corps, each of two regular divisions, and an air component of the RAF. When the French Commander-in-Chief, General Gamelin, visited London in June 1939, he was told that the first two divisions of the British field force would now be able to arrive nineteen days after mobilization, and the whole of the rest of the regular contingent of the BEF in thirty-four days. British follow-up forces would consist of one armoured division, which would be available in early 1940, followed by another much later. As the TA divisions became ready for overseas service between four and six months hence, they too would be made available.

The French would have eighty-four to eighty-six divisions, of which twelve would be needed to guard the Italian frontier. So seventy-two to seventy-four would be available to garrison the Maginot Line, and to stem the German offensive wherever this took place. Along with the four British divisions the Allies could muster at minimum seventy-six divisions. Germany would be able to field 116 divisions. It was assumed that the Germans would attack Poland first, and that it was unlikely that France would be attacked until Poland was defeated. The Germans, having the initiative, would be able to deploy their greater strength at their main point of effort, whereas the Allies would be forced to cover the whole 500 miles of front from Switzerland to the North Sea until the Germans showed their hand.

The Germans also outnumbered the Allies in the air. At this stage, with four months to go before war broke out, the Germans could muster a total of 3,700 aircraft of all types against the Allied total of 2,634. If Italy came into the war she would bring another 1,400 aircraft into the battle.

Staff talks were not held with Belgium or Holland. Both countries hoped that their neutrality would protect them from invasion. The Belgians believed that any staff talks with France and Britain would give the Germans the excuse to attack them when the time came to invade France. The Belgians had failed to learn the lessons of history: neutrality in 1914 had not deterred the Germans from attacking them when it suited them to do so as part of their attempt to outflank the French Army. Holland, having managed to retain its neutrality in the First World War, imagined that it could do likewise in any subsequent conflict.

In the months before war broke out, in an atmosphere of growing menace, Britain introduced full conscription, and partially mobilized the Fleet and the Royal Air Force.

*

On 1 September 1939 Germany invaded Poland after bombing her airfields without warning. Britain ordered full mobilization and, honouring her undertaking to come to Poland's assistance if she were attacked, sent an ultimatum to Germany timed to expire on 3 September. The Germans did not respond and, at 11.00 that morning, the Second World War began.

The British government made two other important decisions that day. The first was to appoint General the Viscount Lord Gort as Commander-in-Chief of the BEF. Gort, who was then fifty-three years old, was a highly decorated Grenadier Guardsman who had served with distinction in the First World War, eventually commanding in turn the 4th and 1st Battalions of his regiment and briefly 3rd Guards Brigade. He had been wounded four times, mentioned in despatches on nine occasions and awarded the Military Cross, the Distinguished Service Order with two bars and the Victoria Cross. A man of great personal and moral courage, he was not suited to high command and had been promoted well above his ceiling. It would be hard to better the description of his character by that very great soldier, then Lieutenant General Alan Brooke, commanding II Corps in the BEF, whose diary entry for 21 November 1939 reads: ‘Gort's brain has lately been compared to that of a glorified boy scout! Perhaps unkind but there is a great deal of truth in it.’⁴ On 22 November 1939 his criticism is more measured:

Gort is queer mixture [sic], perfectly charming, very definite personality, full of vitality, energy and joie de vivre, and gifted with great powers of leadership. But he just fails to see the big picture and is continually returning to those trivial details that counted a lot when commanding a battalion, but which should not be the concern of a Commander-in-Chief.⁵

The second decision was to determine how Gort should conduct British operations in France. The British government placed him under the orders of General Georges, commanding the French North-East Theatre of Operations. Gort was told, ‘You will carry out loyally any instructions issued by him.’ He had the right of appeal to his own government if at any time an order given by Georges appeared to imperil the BEF. Gort was also told that, if General Georges wished to detach part of the BEF for operations elsewhere, such an arrangement should only be temporary.

As the Second World War began less than twenty-one years after the end of the First, there were plenty of officers in the British Army with a wealth of fighting experience. Thanks to the slow pace of promotion in peacetime, men who had fought the Germans in the previous contest could be found down to the rank of major. The commanders of I and II Corps were both older than Gort, and had been senior to him before his sudden and unexpected elevation to C-in-C of the BEF. Lieutenant General Sir John Dill of I Corps, who was five years older, had risen in the First World War to be a Brigadier General Staff (BGS) under Haig, and had been a key planner of Haig's final and highly successful offensives in the autumn of 1918. Lieutenant General Alan Brooke of II Corps was three years older than Gort, had a keen brain and was to prove the star corps commander in the BEF.

One of the youngest divisional commanders, at forty-seven, was Major General the Hon. Harold Alexander, commanding the 1st Division in I Corps, lately of the Irish Guards, having commanded a battalion of that regiment at the age of twenty-five in France in the First World War. Always immaculately turned out, nothing ever seemed to worry him. Major General Bernard Montgomery, commanding the 3rd Division in II Corps, was nearly fifty-two years old, and had already crossed swords with Gort when chief instructor at the Staff College at Quetta in what was then India. Gort, director of training on the staff of C-in-C India, had taken exception to Montgomery's self-assertive instructional style. Montgomery never left anyone, however senior, in any doubt about what he thought of them. Brooke was one of the few people he was in awe, and if anything his admiration for him increased as the war progressed. Brigadiers, colonels and lieutenant colonels with fine fighting records in the First World War were plentiful in the 1939–40 BEF. Some would go on to high command later in the war. Others would fade out of the picture.

The transportation of the BEF to France by the Merchant Navy, escorted by the Royal Navy, took place without the loss of a single life. The main ports through which the BEF landed were Cherbourg, Nantes and Saint-Nazaire in western France, the Channel ports through which the 1914–18 BEF had disembarked being deemed too vulnerable to air attack. The two corps of the BEF were deployed hundreds of miles to the east near the Belgian border and took over French positions between Maulde and Armentières, with French First Army on the right and French Seventh Army on the left. This was only the start. As the months passed, the build-up of the BEF continued, until a third corps was operational. By early May 1940, the BEF had grown from four divisions in two corps to ten divisions in three corps. The corps commanders were: I Corps, Lieutenant General M. G. H. Barker, who had taken over from Lieutenant General Sir John Dill on his appointment as Vice Chief of the Imperial General Staff (VCIGS); II Corps, Lieutenant General A. F. Brooke; and III Corps, Lieutenant General Sir Ronald Adam Bt. Meanwhile everybody waited for Hitler to begin his assault in the west, having carved up Poland in less than a month with his new ally the Soviet Union.

The German Army had used the opportunity of sending ‘volunteers’ to fight on Franco's side in the Spanish Civil War of 1936–9 to practise some of its techniques and theories. But, much more important, the war in Poland provided an excellent live-firing rehearsal for what was to follow in France six months later. The Germans learned a number of useful lessons, and were able to hone their procedures for employing battle groups, infantry–tank co-operation tactics, and the use of aircraft to provide intimate support for ground formations, as well as the necessary liaison and communications to orchestrate the modern all-arms battle.

The British were more up to date than the Germans in just one aspect, that of mechanization or motorization. The BEF that went to France in 1939 was a totally mechanized army. Like the German and French armies it had tanks, but in addition every infantry battalion had ten small open-topped tracked vehicles called Bren-gun carriers designed to provide some mobile protected firepower for the troops. Specially designed motorized vehicles towed all the BEF's guns, and all its supplies were carried in trucks, as were some of the troops. Cars, small vans and motorcycles were provided for commanders, for liaison and for carrying messages. On the outbreak of war, many of these vehicles were requisitioned from civilian firms. Like most other British formations, Major General Montgomery's 3rd Division went to war with laundry and bakers’ vans. None of these commandeered vehicles were really suitable for military use – they were often underpowered and because they did not have four-wheel drive were almost useless across country – but they were better than nothing.

The German Army on the other hand had many horsed formations and units, and persevered with them until the end of the war in 1945. Indeed, the vast majority of formations were not mechanized. Infantry divisions marched on foot, and although each had some 942 motor vehicles, the bulk of their supplies was carried in horse-drawn wagons, 1,200 per division. In addition horse-drawn artillery hugely outnumbered motor-towed pieces. Slow-moving horse-drawn transport should be allocated dedicated roads to avoid blocking the route for its motorized counterpart, but this was not always possible, and the resulting traffic jams sometimes impeded the progress of the army as a whole. Horses consume bulky fodder – yet another unwelcome problem for the logisticians. This horse–motor mix created a quartermaster's nightmare and was to contribute to the failure of the German campaign in Russia that was launched in 1941. Tactically there were two German armies: one fast and mobile, the other slow and plodding. This Achilles heel in the mighty German war machine was to be amply demonstrated in 1940. Only operational and tactical ineptness, principally on the part of the French, prevented the Allies from exploiting this fundamental weakness in the German way of making war.

The French pinned their defence hopes on the Maginot Line, named after the War Minister from 1929 to 1932 who as Sergeant Maginot had been wounded at Verdun early in the First World War. A great deal of the fighting at Verdun in the eleven-month battle of 1916, in which Maginot did not participate, had taken place in and around forts and concrete strongpoints on vital ground defending the city. Paradoxically, before the First World War, the French had scorned the concept of fighting from fortresses, opting instead for aggressive tactics out in the open, attacking the enemy with infantry and light guns regardless of casualties. During the Verdun fighting of 1916, the nature of the terrain and the determination of the French not to cede an inch of ground brought home to them just how important the fortress system was. Loss of some of the key forts nearly cost them the battle. That experience and the terrible losses the French had incurred in the First World War, not only at Verdun but also in numerous engagements both before and after that bloodletting, persuaded them that fortresses and artillery were the answer in any future war. In effect they fell into the age-old trap of planning to fight the next war on the basis of the last one. In 1921, Marshal Pétain, then Supreme Commander, set the scene for the French Army's doctrine on the use of armour, saying, ‘Tanks assist the advance of the infantry, by breaking static obstacles and active resistance put up by the enemy.’⁶ This was not the last time that Pétain, the saviour of Verdun, was to have a baleful influence on his country.

Constructed between 1930 and 1935, and extending from Luxembourg in the north to the Swiss border in the south, the Maginot Line was not really a line, but a string of concrete forts built about three miles apart, interspersed by smaller casemates. Both types were well buried, with only observation cupolas and gun turrets visible, and even these in many cases could be lowered flush with the roof. Advanced warning posts, anti-tank obstacles, wire and mines screened the forts. The garrisons varied from twelve to thirty men in the casemates, and from 200 to 1,200 in the forts. The latter were like underground villages, with barracks, kitchens, generators, magazines and even electric railways to transport men and ammunition from barrack and magazine to the gun positions. Casemates contained machine guns and one 47mm anti-tank gun, with heavy artillery in the forts.

Belgium was still an ally of France while the Maginot Line was under construction and so extending the line to cover the 250 miles of the Franco-Belgian border was considered tactless, as it would send a signal of no confidence in Belgium's capability to resist invasion, and would isolate her on the ‘wrong’ side of the wall. An added disincentive to extending the line was the expense. The eighty-seven miles completed by 1935 had cost 4,000 million francs in excess of the 3,000 million allocated in the budget. Finally, an extension of the line would run through the heavily industrialized region of Lille–Valenciennes on the Belgian border, causing major disruption to French industry. Experience in the First World War had persuaded the French that, if they were to avoid losing this northern industrial region, they would have to stop the invader before he crossed the French frontier. So when Belgium elected for a policy of strict neutrality, the French realized that they would have to enter Belgian territory from the west the moment the Germans invaded it from the east. In this event, instead of fighting from behind the concrete and steel of the Maginot Line on which so much treasure had been spent, the French would be forced to engage in a mobile battle of encounter in open country, a contest for which they were neither mentally prepared nor organized.

The French aimed to fight a methodical battle under a system of rigid centralization and adherence to orders from the top. Unit and formation commanders were supposed to remain at their command posts – the theory being that here, at the centre of communications, they were best placed to receive information and orchestrate the battle. This of course begged the question what one should do if the communications did not work. It was a question that demanded an answer, but the French failed to provide one, and it was a key ingredient in their defeat. For there were few radios in French units and formations, and communication was mainly by messengers or by telephone, using either the civilian system or lines laid by the military. Initiative in subordinate commanders at whatever level was frowned upon. No one was trained to react to the unexpected, and therefore how to work through the chaos. The French doctrine ignored the German commander Helmuth von Moltke's dictum that ‘no plan of operations will ever extend, with any sort of certainty, beyond the first encounter with the hostile main force’, and that success in battle was, and still is, gained by the commander's ability ‘to recognize the changed situation, to order its foreseeable course and to execute this energetically’.

French planning envisaged that as soon as the enemy attacked he was to be stopped by concentrated artillery fire and static defence, rather than by counter-attack. Local reserves would be placed in front of enemy penetrations to slow him down and eventually stop him. Meanwhile local superiority of men and equipment would be assembled, and then, and only then, would counter-attacks be mounted. The armour would not be employed in mass, but in penny packets accompanying the infantry as mobile pillboxes. Even had the communications worked, this rigid, pedestrian operational concept was hardly the best way to fight a mobile enemy. Once the two-way flow of communications was slowed by enemy interdiction, or even brought to a complete standstill, commanders sitting in their command posts would be completely out of touch and unable to influence events.

The German system was totally the opposite, and stressed personal initiative and what modern soldiers call mission command. Subordinates were told what their superior's mission was, and were expected to adapt their plans and the execution of them to achieve it, and to exploit a changing situation to their advantage, while their superiors supported them with all the means at their disposal. Everybody was trained to command at least one if not two levels above their own, and therefore able to take over when superiors became casualties. The leaders of Nazi Germany knew that their country was not well placed economically to fight a long war, but instead had to win swiftly. Thus was born the principle of lightning war, Blitzkrieg, which, following Moltke's teachings, demanded flexibility and the will to win. The German Army was adept at combining mass and aggressive tactics, and in achieving this the commander's mental alertness and drive were essential factors, for the force of his personality affected the whole of his command.

The Germans often used a tactic that today we would call recce pull. Armoured battle groups preceded by reconnaissance would find, or lever open, the weak spots in the enemy defence and, using radio communications, ‘pull’ the main force through behind them; if necessary the main force would switch its axis on to the new line. This is the opposite of everybody bashing forward in a setpiece attack supported by a mass of artillery, only to come up against a rock-like defence. The success of mission command and recce pull depended not only on commanders being well forward where they could ‘read’ the battle, but also on their being in a position to communicate the necessary orders to take account of the changing situation, either face to face with subordinates or by radio. The German system demanded good secure radio communications, and they had them. In addition, German commanders were able to call upon support from their air force, not least dive-bombers that they used in lieu of artillery, particularly if they had advanced beyond the range of their guns. In this way the Germans fought a true all-arms battle, with infantry, armour, artillery and air. Their armour and mechanized infantry were concentrated in elite armoured (panzer) formations, with tanks used in mass.

For the Germans had taken note of British writings and experimentation on armour. Above all, Captain Heinz Guderian, who in the First World War had been on the staff of the German Crown Prince at Verdun, had become convinced that any future war should be fought very differently. He studied the works of Liddell Hart and Fuller and saw the importance of armoured formations, with tanks taking the leading role, not just as adjuncts to infantry. By 1931 he was commanding a motorized battalion equipped with dummy tanks – all that Germany was allowed under the terms of the 1919 Treaty of Versailles. He kept abreast of experiments by Brigadier Hobart's British 1st Tank Brigade on Salisbury Plain in 1934 by employing a local tutor to translate the articles Liddell Hart wrote reporting these exercises. The following year Guderian published a book Achtung – Panzer!, which analysed the successes and failures of the Allied use of tanks during the First World War – the Germans having used tanks only fitfully during that war, and those mainly captured Allied ones. He concluded that what was needed was a fast-moving, medium ‘breakthrough’ tank, not a heavy infantry-support tank of the kind fielded by the French Army. Hitler's accession to power saw Guderian's theories turned into reality, and by 1935 he was commanding the 2nd Panzer Division. The first pamphlets issued to the new panzer divisions were based on British Army manuals on the use of armour, not on the French equivalent, because of the rigidity of the latter's doctrine on the relationship between armour and infantry. Achtung – Panzer! was never translated into French or English, nor was it studied at staff colleges or by the general staffs of either country, although it foretold precisely how Guderian would carry out the breakthrough at Sedan in 1940.

At this point it might be helpful to lay to rest some of the myths about the relative strengths and types of armour on both sides. The ultimate German success has been ascribed to superiority in the numbers and types of equipment, especially tanks. The French possessed some 4,000 armoured fighting vehicles of all types. Of these around 2,000 were fit for modern warfare. A good proportion of these modern tanks were the S-35s (known as Somuas from the initials of the maker). This was one of the best tanks in service in the world, with a 47mm turret-mounted gun. The French also had some slower but more heavily armoured Char B1s, with a hull-mounted short-barrelled 75mm gun, and a 47mm in the turret. The Somuas were grouped in three light mechanized divisions (divisions légères méchaniques – DLMs), very like the German light divisions in that they comprised motorized infantry with a powerful tank element. The excellent Somua medium tank was more heavily armoured, as fast as any contemporary German tank and, except for the Panzer Kampfwagon Mk IV, had a heavier gun. The Char B1s were grouped in three armoured divisions (divisions cuirassées). These had only recently formed and had undergone little or no collective training. A DLM had 220 tanks compared with only 150 in a division cuirassée. The DLMs were allocated to separate armies, and the divisions cuirassées to the reserve: one to the general reserve and two to the reserves of the French First Army Group in the centre, and deployed piecemeal.

The Germans had 2,539 tanks at their disposal when they started their offensive in the west, but of these 1,478 were obsolete Mk Is and Mk IIs, whose main armament consisted only of machine guns or 20mm cannon. The only battleworthy tanks were 349 Mk IIIs with a 37mm gun main armament, 334 Czech tanks also with 37mm guns, and 278 Mk IVs, which in 1940 had a short-barrelled 75mm and were intended as a close-support tank for the Mk IIIs. The Mk IVs were not upgunned until later in the war. So the French outnumbered the Germans in battleworthy tanks.

The British fielded three types of tank: the light Mk VI with one .303in and one .55in machine gun; three Marks of cruiser tank each with a 2-pounder main armaments; and two Marks of infantry tank. The Mk I infantry tank had a .303in machine gun, and the far heavier Mk II or Matilda had a 2-pounder and a .303 machine gun. One of the legacies of the preaching by Liddell Hart and Fuller on the subject of armoured warfare was that the British went to war with these three types of tanks: light tanks for reconnaissance; with cruiser tanks grouped in armoured divisions, highly mobile but weak in firepower; and infantry tanks suitable only for infantry support. The correct answer, which took the British most of